HD 60364-4-444:2010

SLOVENSKI STANDARD
01-januar-2011
1DGRPHãþD
SIST R064-004:2000
1L]NRQDSHWRVWQHHOHNWULþQHLQãWDODFLMHGHO=DãþLWQLXNUHSL=DãþLWDSUHG
QDSHWRVWQLPLLQHOHNWURPDJQHWQLPLPRWQMDPL
Low-voltage electrical installations - Part 4-444: Protection for safety - Protection against
voltage disturbances and electromagnetic disturbances
Elektrische Anlagen von Gebäuden - Teil 4-444: Schutzmaßnahmen - Schutz gegen
Störspannungen und elektromagnetische Störgrößen
Installations électriques à basse tension - Partie 4-444: Protection pour assurer la
sécurité - Protection contre les perturbations de tension et les perturbations
électromagnétiques
Ta slovenski standard je istoveten z: HD 60364-4-444:2010
ICS:
91.140.50 Sistemi za oskrbo z elektriko Electricity supply systems
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

HARMONIZATION DOCUMENT
HD 60364-4-444
DOCUMENT D'HARMONISATION
May 2010
HARMONISIERUNGSDOKUMENT
ICS 91.140.50 Supersedes R064-004:1999

English version
Low-voltage electrical installations -
Part 4-444: Protection for safety -
Protection against voltage disturbances and electromagnetic
disturbances
(IEC 60364-4-44:2007 (CLAUSE 444), modified)

Installations électriques à basse tension - Errichten von Niederspannungsanlagen -
Partie 4-444: Protection pour assurer la Teil 4-444: Schutzmaßnahmen –
sécurité - Schutz bei Störspannungen und
Protection contre les perturbations de elektromagnetischen Störgrößen
tension et les perturbations (IEC 60364-4-44:2007 (CLAUSE 444),
électromagnétiques modifiziert)
(CEI 60364-4-44:2007 (CLAUSE 444),
modifiée)
This Harmonization Document was approved by CENELEC on 2010-05-01. CENELEC members are bound to
comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for implementation of this
Harmonization Document at national level.

Up-to-date lists and bibliographical references concerning such national implementations may be obtained on
application to the Central Secretariat or to any CENELEC member.

This Harmonization Document exists in three official versions (English, French, German).

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus,
the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy,
Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia,
Spain, Sweden, Switzerland and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Management Centre: Avenue Marnix 17, B - 1000 Brussels

© 2010 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. HD 60364-4-444:2010 E

Foreword
The text of the International Standard IEC 60364-4-44:2007, Clause 444, prepared by IEC TC 64,
Electrical installations and protection against electric shock, together with the common modifications
prepared by CENELEC TC 64, Electrical installations and protection against electric shock, was
submitted to the formal vote and was approved by CENELEC as HD 60364-4-444 on 2010-05-01.
This European Standard supersedes R064-004:1999.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN and CENELEC shall not be held responsible for identifying any or all such patent
rights.
The following dates were fixed:
– latest date by which the HD has to be implemented
at national level by publication of a harmonized
national standard or by endorsement (dop) 2011-05-01

– latest date by which the national standards conflicting
with the HD have to be withdrawn (dow) 2013-05-01
In this document, the common modifications are indicated by a vertical line at the left margin of the text.
Clauses, subclauses, notes, tables and figures which are additional to those of Clause 444 of
IEC 60364-4-44:2007 are prefixed “Z”.
__________
- 3 - HD 60364-4-444:2010
444 Measures against electromagnetic influences
444.0 Introduction
Clause 444 provides requirements and recommendations to enable avoidance and reduction of
electromagnetic disturbances.
The document, Clause 444, is intended for architects and for those involved in the design, installation and
maintenance of electrical installations.
Electromagnetic Interference (EMI) disturbs or damages information technology systems (ICT), broadcast
communication technologies (BCT), command, control and communication (CCCB), process monitoring,
control and automation systems (PMCA). Currents due to lightning, switching operations, short-circuits
and other electromagnetic phenomena may cause overvoltages and electromagnetic interference.
These effects can occur
- where large conductive loops exist,
- where different electrical wiring systems are installed in common routes, e.g. power supply,
communication, control or signal cables.
Power cables carrying large currents with a high rate of rise of current (di/dt) can induce overvoltages in
command, control and communication cables of electrical installation systems, which can influence or
damage the connected electrical equipment.
444.1 Scope
To provide requirements and recommendations for electrical installations in order to avoid or reduce the
impact of electromagnetic disturbances.
The rules of this part do not apply to systems that are wholly or partly under the control of public
power supply companies (see scope of HD 60364-1:2008) although voltage and electromagnetic
disturbances may be conducted or induced into electrical installations via these supply systems.
444.2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.

EN 50117-4-1:2008 Coaxial cables - Part 4-1: Sectional specification for cables for BCT cabling in
accordance with EN 50173 - Indoor drop cables for systems operating at
5 MHz - 3 000 MHz
EN 50173-1:2007 Information technology - Generic cabling systems - Part 1: General
requirements
EN 50174-2:2009 Information technology - Cabling installation - Part 2: Installation planning and
practices inside buildings
EN 50174-3:2003 Information technology - Cabling installation - Part 3: Installation planning and
practices outside buildings
EN 50288 series Multi-element metallic cables used in analogue and digital communication and
control
EN 50310:2006 Application of equipotential bonding and earthing in buildings with information
technology equipment
EN 60950-1 Information technology equipment - Safety - Part 1: General requirements
(IEC 60950-1)
EN 61000-6-x series Electromagnetic compatibility (EMC) - Part 6-x: Generic standards
(IEC 61000-6-x series)
EN 61386 series Conduit systems for cable management (IEC 61386 series)
EN 61558-2-1 Safety of power transformers, power supplies, reactors and similar products -
Part 2-1: Particular requirements and tests for separating transformers and
power supplies incorporating separating transformers for general applications
(IEC 61558-2-1)
EN 61558-2-4 Safety of transformers, reactors, power supply units and similar products for
supply voltages up to 1 100 V - Part 2-4: Particular requirements and tests for
isolating transformers and power supply units incorporating isolating
transformers (IEC 61558-2-4)
EN 61558-2-6 Safety of transformers, reactors, power supply units and similar products for
supply voltages up to 1 100 V - Part 2-6: Particular requirements and tests for
safety isolating transformers and power supply units incorporating safety
isolating transformers (IEC 61558-2-6)
EN 61558-2-15 Safety of power transformers, power supply units and similar - Part 2-15:
Particular requirements for isolating transformers for the supply of medical
locations (IEC 61558-2-15)
EN 62305-3 Protection against lightning - Part 3: Physical damage to structures and life
hazard (IEC 62305-3)
HD 60364-1:2008 Low-voltage electrical installations - Part 1: Fundamental principles,
assessment of general characteristics, definitions (IEC 60364-1:2005, mod)
HD 60364-4-41:2007 Low-voltage electrical installations - Part 4-41: Protection for safety - Protection
against electric shock (IEC 60364-4-41:2005, mod.)
1)
HD 60364-5-52:200X Low-voltage electrical installations - Part 5-52: Selection and erection of
electrical equipment - Wiring systems (IEC 60364-5-52:2009)
HD 60364-5-54:2007 Low-voltage electrical installations - Part 5-54: Selection and erection of
electrical equipment - Earthing arrangements, protective conductors and
protective bonding conductors (IEC 60364-5-54:2002, mod.)
IEC/TR 61000-2-5:1995 Electromagnetic compatibility (EMC) - Part 2: Environment - Section 5:
Classification of electromagnetic environments. Basic EMC publication
ETSI EN 300 253:2002 Equipment Engineering (EE) - Earthing and bonding of telecommunication
equipment in telecommunication centres

444.3 Definitions
See HD 60364-1:2008 for basic definitions. For the purposes of this document, the following definitions
apply:
444.3.1
bonding network, BN
set of interconnected conductive structures that provides an “electromagnetic shield” for electronic
systems and personnel at frequencies from direct current (DC) to low radio frequency (RF)
NOTE The term “electromagnetic shield” denotes any structure used to divert, block or impede the passage of electromagnetic
energy. In general, a BN does not need to be connected to earth but BN considered in the present document will have an earth
connection
[3.1.2 of EN 50310:2006]
1)
At draft stage.
- 5 - HD 60364-4-444:2010
444.3.2
bonding ring conductor, BRC
an earthing bus conductor which forms a closed connecting ring
[3.1.3 of EN 50310:2006]
NOTE Normally a bonding ring conductor has multiple connections to the CBN and therefore improves its quality.
444.3.3
common equipotential bonding system
common bonding network, CBN
equipotential bonding system providing both protective-equipotential-bonding and functional-
equipotential-bonding
[IEV 195-02-25]
444.3.4
equipotential bonding
provision of electric connections between conductive parts, intended to achieve equipotentiality
[IEV 195-01-10]
444.3.5
earth-electrode network
part of an earthing arrangement comprising only the earth electrodes and their interconnections
[IEV 195-02-21]
444.3.6
meshed bonding network, MESH-BN
bonding network in which all associated equipment frames, racks and cabinets and usually the DC power
return conductor, are bonded together as well as at multiple points to the CBN.
[3.1.2 of ETSI EN 300 253:2002-04]
NOTE The MESH-BN enhances the effect of the CBN.
444.3.7
by-pass conductor, PEC
conductor usually laid along the cable route to provide a low impedance connection between the earthing
arrangements at the ends of the cable route
[IEV 195-02-29]
NOTE See Figure 44R1 of the present document

444.4 Mitigation of electromagnetic interference (EMI)
Consideration shall be given by the designer and installer of the electrical installation to the measures
described below for reducing the electric and magnetic influences on electrical equipment.
Only electrical equipment, which meets the requirements in the appropriate EMC standards or the EMC
requirements of the relevant product standard shall be used, see also 515.3.1.2.
444.4.1 Sources of EMI
Electrical equipment sensitive to electromagnetic influences should not be located close to potential
sources of electromagnetic emission such as
– switching devices for inductive loads,
– electric motors,
– fluorescent lighting,
– welding machines,
– rectifiers,
– choppers,
– frequency converters (e.g. invertors) and regulators,
– power correction devices
– lifts,
– transformers,
– switchgear,
– power distribution bars.
444.4.2 Measures to reduce EMI
The following measures reduce electromagnetic interference.
a) The installation of surge protection devices and/or filters for equipment sensitive to electromagnetic
influences is recommended to improve electromagnetic compatibility with regard to conducted
electromagnetic phenomena.
b) Conductive sheaths (e.g. armouring, screens) of cables should be bonded to the CBN, if any.
c) Inductive loops should be avoided by selection of a common route (according to 444.6) for power,
signal and data circuits wiring.
d) Power and signal cables should be kept separate and should, wherever practical, cross each other at
right-angles (see 444.6.2).
e) Use of cables with concentric conductors to reduce currents induced into the protective conductor.
f) Use of symmetrical multicore cables (e.g. screened cables containing separate protective conductors)
for the electrical connections between converters and motors, which have frequency controlled
motor-drives.
g) Use of signal and data cables according to the EMC requirements of the manufacturer’s instructions.
h) Where a lightning protection system is installed,
– power and signal cables shall be separated from the down conductors of lightning protection
systems (LPS) by either a minimum distance or by use of screening. The minimum distance shall
be determined by the designer of the LPS in accordance with EN 62305-3;
i) Where screened signal or data cables are used, care should be taken to limit the fault current from
power systems flowing through the screens and cores of signal cables, or data cables, which are
earthed. Additional conductors may be necessary, e.g. a by-pass conductor for screen reinforcement;
see Figure 44.R1.
I
fault
By-pass conductor for screen reinforcement
IEC  050/06
Figure 44.R1 - By-pass conductor for screen reinforcement to provide
a common equipotential bonding system
NOTE 1 The provision of a by-pass conductor in proximity to a signal, or data, cable sheath also reduces the area of the loop
associated with equipment, which is only connected by a protective conductor to earth. This practice considerably reduces for
instances the effects of Lightning Electromagnetic Pulse (LEMP).

- 7 - HD 60364-4-444:2010
j) Where screened signal cables or data cables are common to several buildings supplied from a
TT-system, a by-pass equipotential bonding conductor should be used; see Figure 44.R2. The by-
pass conductor shall have a minimum cross-sectional area of 16 mm² Cu or equivalent. The
equivalent cross-sectional area shall be dimensioned in accordance with 544.1 of HD 60364-5-
54:2007.
L1
L2
L3
N
Building 1 Building 2 Building 3
Substitute or by-pass equipotential
bonding conductor
Screened signal cable
IEC  051/06
Figure 44.R2 - Example of a substitute or by-pass equipotential bonding conductor in a TT-system
NOTE 2 Where the earthed shield is used as a signal return path, coaxial cables with multiple isolated screens may be
used.
NOTE 3 It is recalled that if the consent according to 411.3.1.2 (last paragraph) cannot be obtained, it is the
responsibility of the owners or operators to avoid any danger due to the exclusion of those cables from the connection to the
main equipotential bonding.
NOTE 4 The problems of earth differential voltages on large public telecommunication networks are the responsibility of
the network operator, who may employ other methods.
k) Equipotential bonding connections should have an impedance as low as possible
– by being as short as possible,
– by having a cross-section shape that results in low inductive reactance and impedance per metre
of route, e.g. a bonding braid with a width to thickness ratio of five to one.
l) Where an earthing bar is intended (according to 444.5.7) to support the equipotential bonding system
of a significant information technology installation in a building, it may be installed as a closed ring.
NOTE 5 This measure is preferably applied in buildings of the telecommunications industry.
444.4.3 TN-system
To minimize electromagnetic influences, the following subclauses apply.
444.4.3.1 TN-C-systems shall not be used in newly constructed buildings containing, or likely to
contain, significant amounts of information technology equipment. It is recommended that TN-C systems
should not be maintained in existing buildings containing, or likely to contain, significant amounts of
information technology equipment.
NOTE It is probable that TN-C installations will have load or fault current diverted via equipotential bonding into metallic
infrastructures (e.g. piping, beams) within a building.

444.4.3.2 In newly constructed buildings, TN-S systems shall be installed downstream of the origin of
the installation; see Figure 44.R3A In existing buildings supplied from public low-voltage networks and
which contain, or are likely to contain, significant amounts of information technology equipment, a TN-S
system should be installed downstream of the origin of the installation; see Figure 44.R3A.
NOTE The effectiveness of a TN-S-system may be enhanced by use of a residual current monitoring device, RCM, complying
with EN 62020:1998.
Equipotential bonding L
N
conductor, if necessary
PE
PE, N, L
Equipment 1
Signal or data cable
1)
PE, N, L
Equipment 2
Public supply
IEC  052/06
1) Loops of limited area formed by signal or data cables
Figure 44.R3A - Avoidance of neutral conductor currents in a bonded structure by using the TN-S
system from the origin of the public supply up to and including the final circuit within a building

- 9 - HD 60364-4-444:2010
444.4.3.3 In existing buildings where the complete low-voltage installation including the transformer is
operated only by the user and which contain, or are likely to contain, significant amounts of information
technology equipment, TN-S systems should be installed; see Figure 44.R3B.
Equipotential bonding L
N
conductor, if necessary
PE
PE, N, L
Equipment 1
Signal or data cable
1)
PE, N, L
Equipment 2
IEC  053/06
1) Loops of limited area formed by signal or data cables
Figure 44.R3B - Avoidance of neutral conductor currents in a bonded structure
by using a TN-S system downstream of a consumer’s private supply transformer

444.4.3.4 Where an existing installation is a TN-C-S system (see Figure 44.R4), signal and data cable
loops should be avoided by
– changing all TN-C parts of the installation shown in Figure 44.R4 into TN-S, as shown in
Figure 44.R3A, or
– where this change is not possible, by avoiding signal and/or data cable interconnections between
different parts of the TN-S installation.

L
PEN
3)
PE, N, L
Equipment 1
Signal or data cable
1)
∆U
2)
PE, N, L
Equipment 2
IEC  054/06
1) Voltage drop ∆U is non-zero under normal operation conditions
2) Loop of limited area formed from signal or data cables
3) Extraneous-conductive-part
NOTE In a TN-C-S system, the current, which in a TN-S system would flow only through the neutral conductor, flows also
through the screens or reference conductors of signal cables, exposed-conductive-parts, and extraneous- conductive-parts such as
structural metalwork.
Figure 44.R4 - TN-C-S system within an existing building installation

- 11 - HD 60364-4-444:2010
444.4.4 TT system
In a TT system, such as that shown in Figure 44.R5, consideration shall be given to overvoltages which
may exist between live parts and exposed-conductive-parts when the exposed-conductive-parts of
different buildings are connected to different earth electrodes.

Equipotential bonding
conductor, if necessary
L
N
PE, N, L
PE
Equipment 1
Signal or data cable
1)
PE, N, L
Equipment 2
IEC  055/06
1) Loop of limited area formed from signal or data cables
Figure 44.R5 – TT system within a building installation

444.4.5 IT system
In a three-phase IT system (see Figure 44.R6), the voltage between a healthy line-conductor and an
exposed-conductive-part can rise to the level of the line-to-line voltage when there is a single insulation
fault between a line conductor and an exposed-conductive-part; this condition shall be considered.
NOTE Electronic equipment directly supplied between line conductor and neutral should be designed to withstand such a voltage
between line conductor and exposed-conductive-parts.

Equipotential bonding
conductor, if necessary
L
N
PE, N, L
PE
Equipment 1
Signal or data cable
1)
PE, N, L
Equipment 2
IEC  056/06
1) Loop of limited area formed from signal or data cables
Figure 44.R6 – IT system within a building installation

- 13 - HD 60364-4-444:2010
444.4.6 Multiple-source supply
444.4.6.1 General requirements
As shown in Figure 44.R7A.1, only one connection shall be made between the PEN and PE.
NOTE  This deviates from the requirements of HD 60364-1:2008 since if multiple earthing of the star points of the sources of
supplies is applied, neutral conductor currents may flow back to the relevant star point, not only via the neutral conductor, but also
via the protective conductor as shown in Figure 44.R7A.2. For this reason the sum of the partial currents flowing in the installation is
no longer zero and a magnetic stray field is created, similar to that of a single conductor cable.
In the case of single conductor cables, which carry AC current, an electromagnetic field is generated around the core conductor that
may interfere with some electronic equipment. Harmonic currents produce similar electromagnetic fields but they attenuate more
rapidly than those produced by fundamental currents.

Source 1 Installation Source 2

Earthing for
TT-System
Exposed-conductive-parts
Figure 44.R7A1 – TN and TT multiple-source power supply
with only one connection between PEN and earth

Source 1 Installation Source 2

Earthing for
TT-System
Exposed-conductive-parts
Figure 44.R7A2 – TN and TT multiple-source power supply
with a not allowed multiple connection between PEN and earth
444.4.6.2 TN multiple source power supplies
In the case of TN multiple-source power supplies to an installation, the star points of the different sources
shall, for EMC reasons, be interconnected by an insulated PEN-conductor that is connected to earth
centrally at one and the same point; see Figure 44.R7B.

- 15 - HD 60364-4-444:2010
Source n
Source 2
a)
L1
L2
L3
N
Source 1
PE
a)
c)
d)
b)
Earthing of
the sources
Exposed-conductive-parts
Installation
IEC  058/06
a) No direct connection from either transformer or generator star points to earth is permitted.
b) The conductor interconnecting either transformer or generators star points shall be insulated. This conductor functions as a PEN
conductor and shall be marked as PEN-conductor in accordance with HD 60364-5-51:2006; however, it shall not be connected
with the exposed conductive part of the current-using-equipment and a warning notice to that effect shall be attached to it, or
placed adjacent to it.
c) A blue marking on the whole length is not permitted.
Only one connection between the interconnected star points of the sources and the PE shall be provided. This connection shall
be located inside the main switchgear assembly.
d) Additional earthing of the PE in the installation may be provided.
Figure 44.R7B – TN multiple source power supplies to an installation
with connection to earth of the star points at one and the same point

444.4.6.3 TT multiple-source power supplies
In the case of TT multiple-source power supplies to an installation, it is recommended that the star points
of the different sources are, for EMC reasons, interconnected and connected to earth centrally at only one
point (see Figure 44.R8).
Source n
Source 2
a)
L1
L2
L3
N
Source 1
c)
a)
b)
Earthing of
Exposed-conductive-parts
the source
Installation
IEC  059/06
a) No direct connection from either the transformer or generator star points to earth is permitted.
b) The conductor interconnecting either the transformer, or generator star points, shall be insulated. This conductor functions as
a PEN conductor and shall be marked as PEN-conductor in accordance with HD 60364-5-51:2006; however, it shall not be
connected with the exposed conductive part of the current-using-equipment and a warning notice to that effect shall be
attached to it, or placed adjacent to it.
c) A blue marking on the whole length is not permitted.
Only one connection between the interconnected star points of the sources and the PE shall be provided. This connection
shall be located inside the main switchgear assembly.
Figure 44.R8 – TT multiple-source power supplies to an installation
with connection to earth of the star points at one and the same point

- 17 - HD 60364-4-444:2010
444.4.7 Transfer of supply
In TN systems the transfer from one supply to an alternative supply shall be by means of a switching
device, which switches the line conductors and the neutral, if any (see Figures 44.R9A, 44.R9B and
44.R9C).
Power supply 1 Power supply 2
L1
L1
L2
L2
L3
L3
N
PE
Current using equipment
NOTE This method prevents electromagnetic fields due to stray currents in the main supply system of an installation. The sum of
the currents within one multicore cable must be zero. It ensures that the neutral current flows only in the neutral conductor of the
rd
circuit, which is switched on. The 3 harmonic (150 Hz) current of the line conductors will be added with the same phase angle to
the neutral conductor current.
Figure 44.R9A – Three-phase alternative power supply with a 4-pole switch

L1
L1
L2 L2
L3 L3
N
PE
NOTE A three-phase alternative power supply with an unsuitable 3-pole switch will cause unwanted circulating currents, that will
generate electromagnetic fields which may cause inopportune operation of residual current devices .
.
Figure 44.R9B – Neutral current flow in a three-phase alternative power supply
with an unsuitable 3-pole switch

- 19 - HD 60364-4-444:2010
L
N
PE
UPS-System
Current using
equipment
IEC  062/06
NOTE The earth connection to the secondary circuit of a UPS is not mandatory. If the connection is omitted, the supply in the
UPS-mode will be in the form of an IT system and, in by-pass mode, it will be the same as the low-voltage supply system.
Figure 44.R9C − Single-phase alternative power supply with 2-pole switch
444.4.8 Services entering a building
Metal pipes and the metal armouring of cables shall be bonded to the main earthing terminal by means of
conductors having low impedance. General requirements for bonding of incoming services are given in
HD 60364-5-54:2007. Metal pipes (e.g. for water, gas or district heating) and incoming power and signal
cables should preferably enter the building at the same place.
NOTE Interconnection is only permitted with the consent of the operator of the external service.
444.4.9 Separate buildings
Where different buildings have separate equipotential bonding systems, metal-free fibre optic cables or
other non-conducting systems may be used for signal and data transmission, e.g. microwave signal
transformer for isolation in accordance with EN 61558-2-1, EN 61558-2-4, EN 61558-2-6, EN 61558-2-15
and EN 60950-1.
NOTE 1 The problem of earth differential voltages on large public telecommunication networks is the responsibility of the network
operator, who may employ other methods.
NOTE 2 In case of non-conducting data-transmission systems, the use of a by-pass conductor is not necessary.

444.4.10 Inside buildings
Where there are problems in existing building installations due to electromagnetic influences, the
following measures may improve the situation (see Figure 44.R11):
1) use of metal free fibre optic links for signal and data circuits, see 444.4.9;
2) use of Class II equipment;
3) use of double winding transformers in compliance with EN 61558-2-1 or EN 61558-2-4 or
EN 61558-2-6 or EN 61558-2-15. The secondary circuit should preferably be connected as a TN-S
system but an IT-system may be used where required for specific applications.

- 21 - HD 60364-4-444:2010
Class II Class I
Class I
8)
FE
Distribution
Distribution
board
FE board
Data cable
Floor
3)
3)
Existing electrical
installation, which does
4)
not comply with the
7)
measures given in
FE
this standard.
Class II
PE
Class I
Class I
FE
2)
Distribution
board
6)
FE
Data cable
Floor
SPDs
Conductors going to telecom
exchange or information
7)
technology equipment
FE
PE
5) 1)
PE
Legend
Main earthing
Power supply terminal (MET)
Bonding points of earthing
To earth electrodes
conductors for protective or
e.g. foundation earth electrode
functional purposes
FE  Functional earthing conductor,
Symbol for PE conductor
(optional), used and bonded
according to the operator instructions
Symbol for neutral conductor
Symbol for line conductor
SPDs Surge protective devices IEC  064/06

Reference Description of the illustrated measures Subclause/
standard
1) Cables and metal pipes enter the building at the same place 444.4.8
2) Common route with adequate separations and avoidance of loops 444.4.2
3) Bonding leads as short as possible, and use of earthed conductor parallel to a IEC/TR 61000-2-5:1995
cable 444.4.2
4) Signal cables screened and/or conductors twisted pairs 444.4.12
5) Avoidance of TN-C beyond the incoming supply point 444.4.3
6) Use of transformers with separate windings 444.4.10
7) Local horizontal bonding system 444.5.4
8) Use of class II equipment 444.4.10
Figure 44.R10 - Illustration of measures in an existing building

444.4.11 Protective devices
In addition to the requirements for protective devices given in other parts of HD 60364, protective devices
with appropriate EMC functionality to avoid unwanted tripping due to high levels of transient currents,
should be selected.
444.4.12 Signal cables
Shielded cables and/or twisted pair cables should be used for signal cables.
444.5 Earthing and equipotential bonding
444.5.1 Interconnection of earth electrodes
For several buildings, the concept of dedicated and independent earth electrodes connected to an
equipotential conductor network may not be adequate where electronic equipment is used for
communication and data exchange between the different buildings for the following reasons:
– a coupling exists between these different earth electrodes and leads to an uncontrolled increase of
voltage to equipment;
– interconnected equipment may have different earth references;
– a risk of electric shock exists, specifically in case of overvoltages of atmospheric origin.
All protective and functional earthing conductors within an installation shall be connected to the main
earthing terminal as required by HD 60364-5-54:2007.
Moreover, all earth electrodes associated with a building i.e. protective earth and functional earth, shall be
interconnected (see Figure 44.R11).
In the case of several buildings, where interconnection of the earth electrodes is not possible or practical,
it is recommended that galvanic separation of communication networks is applied, for instance by the use
of fibre optic links.
Protective and functional earthing conductors

Main earthing terminal
Protective earth
Functional
Interconnected earth electrodes
electrode
earth electrode
Separate earth electrode
Figure 44.R11 – Interconnected earth electrodes

- 23 - HD 60364-4-444:2010
Protective and functional bonding conductors shall be connected individually to the main earthing terminal
in such a way that if one conductor becomes disconnected the connections of all the other conductors
remain secured.
444.5.2 Interconnection of incoming networks and earthing arrangements
For dwellings where normally a limited amount of electronic equipment is in use, a protective conductor
network in the form of a star network may be acceptable (see Figure 44.R12).
For commercial and industrial buildings and similar buildings containing multiple electronic applications, a
common meshed bonding system is useful in order to comply with the EMC requirements of different
types of equipment (see Figure 44.R14).
444.5.3 Different structures for the network of equipotential conductors and earthing
conductors
The four basic structures described in the following subclauses may be used, depending on the
importance and vulnerability of equipment.
444.5.3.1 Protective conductors connected to a bonding-ring conductor
An equipotential bonding network in the form of a bonding ring conductor, BRC, is shown in
Figure 44.R16 on the top-floor of the structure. The BRC should preferably be made of copper, bare or
insulated, and installed in such a manner that it remains accessible everywhere, e.g. by using a cable-
tray, metallic conduit (see EN 61386 series), surface mounted method of installation or cable trunking. All
protective and functional earthing conductors may be connected to the BRC.
444.5.3.2 Protective conductors in a star network
This type of network is applicable to small installations associated with dwellings, small commercial
buildings, etc., and from a general point of view to equipment, that is not interconnected by signal cables
(see Figure 44.R12).
Distribution
board
Current using
equipment
Main
earthing
terminal(s)
(MET)
Earthing conductor
Protective conductor
IEC  066/06
Figure 44.R12 – Examples of protective conductors in star network
444.5.3.3 Multiple meshed bonding star network
This type of network is applicable to small installations with different small groups of interconnected
communicating equipment. It enables the local dispersion of currents caused by electromagnetic
interference (see Figure 44.R13).

Current using equipment
y
y
Distribution
y
y
board
y
y
y y
Main earthing
terminal(s)
y y
y
y
Earthing conductors (protective or functional)
Functional bonding conductors. The length of these conductors
y
shall be as short as possible (for instance < 50 cm)
IEC  067/06
Figure 44.R13 – Example of multiple meshed bonding star network
444.5.3.4 Common meshed bonding star network
This type of network is applicable to installations with high density of communicating equipment
corresponding to critical applications (see Figure 44.R14).
A meshed equipotential bonding network is enhanced by the existing metallic structures of the building. It
is supplemented by conductors forming the square mesh.
The mesh-size depends on the selected level of protection against lightning, on the immunity level of
equipment part of the installation and on frequencies used for data transmission.
Mesh-size shall be adapted to the dimensions of the installation to be protected, but shall not exceed
2 m x 2 m in areas where equipment sensitive to electromagnetic interferences is installed.
It is suitable for protection of private automatic branch exchange equipment (PABX) and centralized data
processing systems.
In some cases, parts of this network may be meshed more closely in order to meet specific requirements.

Bonding connection Mesh
Current using
Distribution
equipment
board
Main earthing
terminal(s)
(MET)
Bonding conductors
(protective or functional)
Functional bonding conductors. The length of these
conductors shall be as short as possible, for instance
< 50 cm; see 444.5.5.
IEC  068/06
Figure 44.R14 – Example of a common meshed bonding star network

- 25 - HD 60364-4-444:2010
444.5.4 Equipotential bonding networks in buildings with several floors
For buildings with several floors, it is recommended that, on each floor, an equipotential bonding system
be installed; see Figure 44.R15 for examples of bonding networks in common use; each floor is a type of
network. The bonding systems of the different floors should be interconnected, at least twice, by
conductors.
Equipotential BRC
bonding network
Common meshed
bonding network
Multiple star/mesh
bonding network
Main earthing terminal(s)
star bonding network
Structural metalwork
Foundation
earth electrode
IEC  069/06
Figure 44.R15 – Example of equipotential bonding networks in structures
without lightning protection systems
444.5.5 Functional earthing conductor
Some electronic equipment requires a reference voltage at about earth potential in order to function
correctly; this reference voltage is provided by the functional earthing conductor.
Conductors for functional earthing may be metallic strips, flat braids and cables with circular cross
section.
For equipment operating at high frequencies, metallic strips or flat braids are preferred and the
connections shall be kept as short as possible.
No colour is specified for functional earthing conductors. However, the colours green-and-yellow specified
for earthing conductors shall not be used. It is recommended that the same colour is used throughout the
whole installation to mark functional earthing conductors at each end.

For equipment operating at low frequencies, cross sectional areas as indicated in 544.1.1 of
HD 60364-5-54:2007 are considered satisfactory, independent of the conductor shape; see 444.4.2b) and
k).
444.5.6 Commercial or industrial buildings containing significant amounts of information
technology equipment
The following additional specifications are intended to reduce the influences of electromagnetic
disturbances on the information technology equipment operation.
In severe electromagnetic environments, it is recommended that the common meshed bonding star
network described in 444.5.3.3 be adopted.
444.5.6.1 Sizing and installation of bonding ring network conductors
Equipotential bonding designed as a bonding ring network shall have the following minimum dimensions:
– either flat copper cross-section: 30 mm x 2 mm, or
– round copper diameter: 8 mm.
Bare conductors shall be protected against corrosion at their supports and on their passage through
walls.
444.5.6.2 Parts to be connected to the equipotential bonding network
The following parts shall also be connected to the equipotential bonding network:
– conductive screens, conductive sheaths or armouring of data transmission cables or of information
technology equipment;
– earthing conductors of antenna systems;
– earthing conductors of the earthed pole of DC supply for information technology equipment;
– functional earthing conductors.
444.5.7 Earthing arrangements and equipotential bonding of information technology
installations for functional purposes
444.5.7.1 Earthing bar
Where an earthing bar is required for functional purposes, the main earthing terminal (MET) of the
building may be extended by using an earthing bar. This enables information technology installations to
be connected to the main earthing terminal by the shortest practical route from any point in the building.
Where the earthing bar is erected to support the equipotential bonding network of a significant amount of
information technology equipment in a building, it may be installed as a bonding ring network.
NOTE 1 The earthing bar may be bare or insulated.
NOTE 2 The earthing bar should preferably be installed so that it is accessible throughout its length, e.g. on the surface of
trunking. To prevent corrosion, it may be necessary to protect bare conductors at supports and where they pass throughout walls.
444.5.7.2 Cross-sectional area of the earthing bar
The effectiveness of the earthing bar depends on the routing and the impedance of the conductor
employed. For installations connected to a supply having a capacity of less than 200 A per phase, the
requirements of HD 60364-5-54:2007 apply. For installations connected to a supply having a capacity of
200 A per phase or more, the cross-sectional area of the earthing bar shall be not less than 50 mm²
copper and shall be dimensioned in accordance with 444.4.2k), subject to the requirements of
HD 60364-5-54:2007.
NOTE This statement is valid for frequencies up to 10 MHz.

- 27 - HD 60364-4-444:2010
Where the earthing bar is used as part of a DC return current path, its cross-sectional area shall be
dimensioned according to the expected DC return currents. The maximum DC voltage drop along each
earthing bar, dedicated as DC distribution return conductor, shall be designed to be less than 1 V.
444.5.7.Z1 Earth connection to meet EMC requirements for communication cubicle/cabinets and
racks
Earth connections should be a low impedance path, the earth cable shall not be coiled or doubled back
on its self. Suitable precautions shall be taken to avoid any potential difference between the existing earth
and a new installation.
Where shielded cables are terminated within a cabinet, a separate earth connection with a low
impedance shall be installed from the point of termination to the earth point within the cabinet. The
metallic frame of the communication cabinet/frame shall not be used as the only earth connection.
For the situation where there are multiple cabinets, each cabinet shall be connected to the earth
separately. Where multiple cabinets are located within one area, an earthing bar shall be fitted within the
area. The length of the earthing bar shall be sufficient for the immediate requirements and have at least a
20 % allowance for future growth. The earthing bar should be fitted with a disconnection/test point
The cross sectional areas of the protective conductor shall be chosen according to HD 60364-5-54:2007,
Clause 543. Nevertheless the cross-sectional area of the conductor shall not be less than the following:
• 4 mm² for a cabinet s
...